


Perpetuum Mobile

by JeanBiscuit



Category: Shingeki no Kyojin | Attack on Titan
Genre: F/M, Oral Sex, Reader-Insert, Reader-Interactive, Rough Sex, Smut, whoops
Language: English
Status: Completed
Published: 2014-06-05
Updated: 2014-06-05
Packaged: 2018-02-03 11:18:42
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 4,583
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/1742861
Author URL: https://archiveofourown.org/users/JeanBiscuit/pseuds/JeanBiscuit
Summary: <blockquote class="userstuff">
              <p>did someone say jean/reader smut?</p><p> </p><p>i'm not even a little bit sorry</p>
            </blockquote>





	Perpetuum Mobile

**Author's Note:**

> *Let's Get It On by Marvin Gaye plays in the distance*  
> slight springles and eremika because i can't help myself

It was almost like he was trying to drive you insane.  It was early morning, and your brain hadn’t quite registered everything around you yet, except for Jean Kirschtein.  That smug asshole was leaning against the wall with one shoulder, arms crossed, chatting with Connie.  You didn’t know what it was about that stupid pose, maybe it was his dumb muscles flexing as he shifted, those rippling biceps that always held you so close, that crushed you after an especially dangerous expedition, that held you to his chest as the two of you tangled under the sheets –

Everything came into focus remarkably fast as electric tingles crackled their way through your frame.  You were suddenly very aware of Sasha speaking to you, completely unaware that your mind was occupied with – uh – _other_ matters.  You heard your name being called, but it was as if the two of you were standing at opposite sides of a busy marketplace. You blinked and turned to the girl, not even bothering to fix your expression.  You just hoped that the dazed look you knew you had would pass off for morning tiredness.

“So?  Whaddayah think, [First]?” Sasha asked excitedly, bouncing on the balls of her feet.

“Sorry, what?” you mumbled absentmindedly, tousling your messy mop of hair.

“About my plan, dummy,” she groaned, pursing her lips at you disapprovingly.

A tiny bell rang somewhere in the back of your mind, a faint recollection of Sasha deliberating how she was going to confess to Connie, or something like that.

Spring certainly had come to the little cabin in the woods.  The last bits of snow had melted off of the ground, little green buds were beginning to appear on the trees, and the weather was finally starting to warm up.  _About damn time,_ you thought, remembering those bitterly cold nights standing watch at the makeshift guard tower, completely convinced that you would be dead of hypothermia by morning, so much so that every night you were unfortunate enough to draw night duty, you spent half of it carving your last will and testament into the ice on the railings.

But that was all behind you, and you would’ve been outside enjoying the fresh air if your mind hadn’t been completely occupied with thoughts of Jean pounding you into the mattress.

But you had other matters to attend to at the moment, namely, Sasha and her love life.

“You want me to be honest?” you asked, throwing all caution away, looking her straight in the eye.  She nodded eagerly.  “Your plan sucks.  Here’s what you do.  You make him something.  Whatever his favorite food is, I don’t fucking know.  When he gets food around his mouth or whatever, as he undoubtedly will, say, “Hey, Connie, you got something there,” then go in for a kiss.  Bam.  Done.  Get married, have babies, whatever, now can I please go get breakfast?”

Sasha looked at you in utter reverence, as if she was witnessing the birth of a new deity. 

“My savior!” she screeched at the top of her lungs, tackling you in a hug, and you were uncomfortably aware of Jean’s eyes on you.

“Sasha,” you whined, trying to pry her off of you.  “I wanna go eat.”

At the mention of word “eat” she bolted away from you with inhuman speed, careening her way down the stairs toward the kitchen, limbs flying all over the place.  Connie, of course, followed her, and it was just you and Jean in that suddenly too long hallway.  Since the little abode you had been “hand-picked” to stay in was really rather small, all of the bedrooms were set against one hallway, a room for the boys, a room for the girls, and two for Levi and Hanji. 

“So, what was that all about?” Jean drawled, and you saw his familiar smirk inching its way across his face.  But instead of annoyance, all you felt was the hunger stirring in the pit of your stomach growing, as you remembered the way his smirk felt against your skin as he kissed and sucked at the skin of your neck.

“Nothing, dumbass,” you snapped, rolling your eyes, trying to stuff your hormones in a box until the next time you two were alone. 

“Didn’t look like nothing,” he pressed, stepping closer to you, and you desperately wanted to tackle him right then and there.  Your clothes suddenly felt too tight, much too tight, and you wanted to tear them all off and feel his hot lips on your skin –

“You were never good at keeping secrets,” you replied in your signature rapid-fire manner.  You were amazed at the steadiness in your voice, but your composure was sure as hell gonna crack if you stayed near him any longer.

“Aw, come on, just this once,” he said quietly as he stepped closer, his voice husky and laced with lust.  It only served to weaken your self-control.

“Sasha’s gonna confess to Connie.  You happy?” you said hastily, crossing your arms in front of you before your hands involuntarily reached out to pull his face to yours.

“Didn’t know Potato Girl had it in her,” Jean said with an appreciative grin.

“Yeah, well, whatever,” you grumbled, turning away.  “Let’s go get breakfast, dumbass.”

“Aw, already?” you heard him mumble from behind you, and suddenly his chest was pressed to your back, you could feel all his muscles rippling against you, and you shuddered.

“They’re right downstairs, you idiot,” you hissed as his hands found their way to your hips and started rubbing lazy circles.

“We’ll make it quick, then,” he whispered in your ear, and you were positive now that this pair of underwear was a goner.  You felt the beginnings of his arousal pressing into your back, and you forced down a moan.  You were more than willing to take him up on his suggestion, but the one rational part of your brain was still alive and kicking, and wouldn’t go down without a fight.

“Dumbass, we have shit we have to do.”

“You sure?” he replied, his hands skimming up your waist, ghosting against the curve of your breasts, and you found you no longer possessed the willpower to push them away.

“You’re such a fucking child,” you spat, whipping around and twisting your fingers in the collar of his shirt.  “Later, okay?”

“Do I at least get a good morning kiss?” he pleaded, sticking out his bottom lip.  You rolled your eyes and sighed irritably, but couldn’t stop yourself as you smashed your lips to his.  He responded immediately, hands twining around your waist and pulling you close, and a small moan escaped from the back of your throat.  His fingers were just starting to skim under your blouse when the sliver of common sense you had left hit you like a truck. 

You managed to pull away, grabbing him by the wrists and jerking him away from your waist.

“We have to look presentable,” you hissed, straightening out your blouse and dusting imaginary dirt off of your trousers.

“Yeah, yeah,” he sighed exasperatedly, running a hand through his copper-blond hair.  “I’m gonna keep you to that promise, though,” he added with a wink, and your cheeks nearly burst into flame.

He managed to dodge your kick, chuckling as he jogged down the stairs.  You followed him, grumbling irritably and trying to fix your hair so it didn’t look as if rats lived in it. 

You emerged on the ground floor to chaos, as per the usual.  Sasha and Connie were piling their plates high with food, ignoring the now routine threats from the Corporal.  Eren, Mikasa, and Armin were already sitting down at the table, discussing something, with Historia at the other end, nudging at her food disinterestedly with her fork.  Jean was wrestling with Sasha for the last bagel, but with a well-placed elbow to Jean’s ribs and a pointed “I’m ensuring your future sex life” look to Sasha, you managed to secure it for yourself.

“Not fair,” Jean groaned, rubbing the spot where you had hit him.  “I wanted a goddamn bagel for once.”

“Then spend less time in the bathroom trying to fix your unfixable appearance, Horseface,” you said breezily as you scooped up a plate and dumped a few spoonfuls of scrambled eggs onto it.  You heard Eren snicker behind you, and felt Jean’s murderous gaze at your back as you plopped down next to Sasha.  Jean took a seat next to Armin across the table and a few seats down, but he still managed to shoot you venomous glances when he got the chance.  You had to admit, he was persistent.

“Alright, brats,” Levi drawled from the head of the table, setting his knife and fork down and daintily dabbing at the corners of his mouth with his napkin.  You had never seen a man or woman put away food as fast as the Lance Corporal, not even Sasha, who sometimes ate as if she hadn’t seen a morsel of food in weeks.  You suspected it had something to do with his supposed underground city origins, but even you didn’t have the courage to bring it up.  “Here’s where you’re assigned today.  Jaegar, you’ll be training with Ackerman and I.”  Eren groaned audibly from down the table, and you couldn’t blame him.  Sparring with Mikasa wasn’t all that bad, since she had a sense of when to stop. Unfortunately, this was a sense the Corporal did not possess.  “Braus, Springer, Reiss, you’re on guard duty.  Braus, you’re in the tower; Springer and Reiss, split up and scan the perimeter.” Sasha and Connie grumbled under their breath, while Historia, as usual, remained silent. You seriously had started to wonder whether this new, totally unfamiliar version of “Christa” possessed any emotions at all.  You almost missed the too-happy, bubbly Christa Renz who you had spent years training and living with.  This new Historia Reiss was barely more than a stranger to you.  “Armin, you’re with Shitty Glasses, you two’re going to observe the local flora or some shit.  Kirschtein, [Last], you get to do housework today.”

Jean groaned loudly, which earned him a swift Levi kick to the leg, but you honestly couldn’t care less about the chores.  You and Jean would be stuck in this house, alone, all day.  It filled you with a strange excitement that sparked warmth in your abdomen again.  You couldn’t even glance in Jean’s direction as you shoveled down the rest of the food on your plate, swallowing in a large gulp and sweeping off to the kitchen to wash your dishes.  As you stood in front of the sink, absentmindedly scrubbing off the remnants of your breakfast, all you could think of was the glorious, completely uninterrupted sex the two of you could have. 

The two of you had only been banging for a few months now, and it had always been short little trysts between assignments, or a stiflingly quiet session at the end of the day.  From day one the both of you tried your absolute hardest to keep everything a secret, and that meant having to muffle your moans in pillows, and doing it standing up, still halfway clothed in a broom closet.  Well, scratch that, quick broom closet sex is strangely exciting, you amended to yourself.  When it wasn’t _every_ session, that is.  You had grown tired of sneaking around, and now there was this one day where you could scream in ecstasy as loud as you wanted, and there was no one within a mile radius to hear you. 

You were happier than you had been in a while.  You finally finished scraping the food off your plate, placed it on the drying rack, quickly wiped your hands with a dish towel, and strode into the common room to find Sasha, Connie, Armin, and Historia already gone, their dishes conveniently left behind, and Eren tottering to the kitchen with Levi and Mikasa’s plates as the two dark-haired soldiers pulled on their boots by the door.  Jean was leaning against the wall near the staircase, and the two of you exchanged a quick glance, and small grins.

“Alright, brats,” Levi snapped as Eren bustled out of the kitchen.  “Don’t burn the fucking house down, don’t have sex everywhere –”

You and Jean both burst into a volley of furious denials, but Levi only rolled his eyes and strode out the door, closing it with a snap behind him.  You waited for the sound of their footsteps to recede into the distance, holding your breath, your heart pounding in your ears.

When the last steps faded, you whipped around, and before Jean could register what was happening you were crushing him to the wall, your lips furiously attacking his.  But a millisecond later reflex kicked in and his arms snaked around your waist, pulling you even closer, your hips involuntarily grinding against his, and you could feel his low groan resonating through your mouth.

“What about – the chores?” Jean panted as he pulled away, hands already working on the buttons of your blouse.

“Screw – the fucking – chores,” you snapped through gritted teeth, grabbing him by the collar and stumbling toward the stairs.

“What’s – with you – huh?” Jean breathed in between kisses, as the two of you managed to make your way up the stairs.

“This is the only – fucking – day – we’ll _ever_ have – where I can scream as loud – as I fucking – want – and we can do it for as long – as we want,” you replied, tripping your way onto the second floor and shoving him to the wall beside his bedroom door.  You saw his pupils dilate with lust, and he whipped around, pushing your body into the wall with his own.  He kissed you with everything he had, his hands skimming up to your breasts, thumbs lightly brushing over your already hard nipples, and you sighed into his mouth. 

He kicked open the bedroom door, dragged you inside, and roughly threw you onto his bed, but you didn’t mind.  All you could think about was Jean, his body, his lips, his –

And suddenly clothes were flying through the air, your trousers were jerked off of your legs, your fumbling hands managing to pry his shirt over his head. He swiftly unbuckled his pants and flung them aside, and you were both in your undergarments, your panting breaths making everything hazy and pleasantly warm. 

Jean settled on top of you, weight balanced on his forearms, and you could feel his arousal pressing tantalizingly close to your center, and you whimpered, jerking your hips up toward his.  A throaty groan bubbled from the back of his throat, as his eyes met yours.  They were filled with a hunger and intensity that sent a thrill through you. You weren’t scared, not in the least.  How could you be?  Roiling energy and anger were what made up your entire existence, and Jean’s entire being was made up of it.  Being with him was like nothing you had ever felt, nothing and everything could hurt you at exactly the same time, but you knew for a fact that even though his hands were slowly unclasping your brassiere and tossing it to the floor, his lips sucking at the soft skin of your neck, he would back off if you asked him to.  You had almost never had a say in anything in your entire life, and now you had the whole world (because, you had discovered, Jean _was_ the world, crazy and stupid as it sounded, but he _was_ ) in the palm of your hand.

His hands kneaded at your breasts, while his lips and tongue sucked and laved along your neck, along your jawline, nipping across your collarbone.  You breathed his name, nothing more than a soft whisper, and his intensity increased tenfold.  He slithered his way down your body, hands kneading at the hard flesh of your abs as he pressed kisses to the smooth skin of your breasts, paying special attention to the marks left by your 3dmg harness.  Through the haze of lust and desire, and between your little moans and whimpers as his touches set every single nerve thrumming, you vaguely wondered what he was doing.

It wasn’t as if the two you hadn’t done this before.  But those times had been fast-paced and rushed, and the only place his lips had thoroughly explored was your neck, since it was the most easily accessible for his mouth as he pounded into you.  But now he was taking his sweet time.  He seemed to want to lick and kiss every single inch of you, but you sure as hell weren’t complaining. 

He slowly made his way down your abdomen, licking the crevices between your abs, his hands kneading the small of your back.  You arched off of the bed, little moans and mewls escaping from your lips that you in your right mind would have been ashamed of.  It was only when his fingers deftly slid your panties from your legs, and his hot breath blew over your center, that your lust-filled brain finally figured it out.

“Y-You don’t – have to,” you panted as he settled into a comfortable position, hands coming up to knead your hipbones in slow, lazy circles.  “There’s – hair –” 

“There’s hair everywhere, dumbass,” he snorted, his voice husky and so thick with lust you almost moaned at the sound.  “Plus, if I didn’t want to, I wouldn’t.”  He inched closer, his nose just barely brushing your lips, but that one simple action made you arch off of the bed once more, and you moaned loudly. 

He chuckled, and pressed a soft kiss to the inside of your thigh, torturously close to where you really wanted him. 

“Don’t – expect me to – return – the favor,” you breathed, your voice still retaining that signature edge even in your sex-driven daze.

“Believe me,” Jean sighed, and the feeling of his hot breath over your core made you whimper.  “This is all the payment I need.”

He pressed a soft kiss to your lips, just above your clit, and your hands dug into the bed sheets, your back arched above the bed.  You chanted his name like a prayer as he licked and sucked and kissed, sending such amazing feelings from the tips of your fingers all the way to your toes.  This sensation was up there with one of the best moments of your life, and you never wanted it to end.  His teeth gently worried your clit, and you yelped, your fingers carving into the sheets, your hips bucking up to meet his mouth.  He chuckled, slowing down for a moment, his tongue lazily licking circles around your entrance, and your hands found their way to his hair.  You ran your fingers through his copper-blond locks, and that was when his tongue abruptly thrust into your entrance.

You practically screamed, your thighs clamping around his head and your fingers tugging at his hair, but he gave no protest or grunt of pain whatsoever.  His tongue pumped in and out of you, and you thought you would implode from all of the feelings assaulting your senses.  Colors burst and faded behind your eyelids as you moaned and yelped loudly, your fingers massaging his scalp, your thighs still steadfast around his head.  One of his hands slid from your hips and snaked its way between your legs, and you bucked wildly as he pumped one, then two, and then finally three fingers inside of you, and a crescendo started to rise, a tight coil roiling around itself in your lower abdomen.  His tongue and his fingers picked up the pace, as if sensing that you were about to tip over the edge, and his tongue popped out of you to lick and suck at your clit, sending you further into ecstasy.

It was only when his fingers curled inside of you, pressing against a spot, a tiny spot, and everything inside of you exploded in a burst of flashing color and euphoria, that you briefly remarked on how the 104th girls were right.  It _did_ exist, and Jean “Horseface” Kirschtein, of all people, had found yours.

His lips and tongue continued to ride you through your orgasm, and you were impressed at his resilience as you came heavily, his tongue lapping up everything you had to offer.

And all of a sudden it was over. You collapsed onto the bed, panting and shaking, your whole body tingling with the aftershocks of what had felt like an earthquake.  Your fingers loosened their hold on his hair, your thighs slowly released him, and you melted like jelly into the mattress.  Jean’s hands had resumed their careful kneading of your hipbones, and you tilted your head, peering to look at him.  He sucked your juices from his fingers, carefully and methodically, and you felt your arousal picking up speed yet again at the sight.  His hooded amber eyes met yours as he licked his lips, and you mewled at the sight, your head crashing back onto the bed.

“How’re you – so good – with your mouth?” you panted as he slithered his way up back up your body, planting spontaneous kisses as he went.  “I thought you said – you’ve never – been with anyone – before?”

“Yep.  No one but you, sweetcheeks,” he drawled cockily, hovering above you and grinning lopsidedly.

“I swear to god, Jean, if you don’t fuck me so hard I can’t walk right this second I’m gonna – ”

“Yeah, yeah,” he said impatiently, placing a quick kiss to the crook of your neck as he shimmied out of his boxers.  You were feeling pretty tired, but as you looked down at his thick member, painfully erect, every semblance of exhaustion left you.  Your whole body was thrumming again, as if he hadn’t just given you the best orgasm of your entire life. 

As he positioned himself in front of you, you quipped, “You know, some French might just make this a whole lot sexier.”

He rolled his eyes, and replied sarcasticallly, “Oh, bien sûr, quelque chose pour vous.”

“Oh, mon amour,” you purred dramatically, bringing up a wrist to rest on your brow. 

With a feral growl, he thrust into you in one move, and you felt as if you had been struck by lightning.  You threw your head back, crying out, as he filled you up to the brim, throbbing within you.

He groaned your name, hands on either side of your head, his eyes staring down into yours.  The lust in his gaze nearly sent you over the edge right there.  There was only a slight problem.

He was stock still within you, apparently relishing the feel of you, but you did not have the fucking patience.

“Kirschtein,” you growled, eyes narrowed.  “You can move, you know.”

With a wicked grin, he readily complied, pulling out almost all the way and slamming back into you with such force that you slid up the bed a few inches.  You cried out, arms circling around his neck to pull him down to you, his face buried in your neck. 

He pounded into you harder than ever, with such intensity and ferocity it was as if he was trying to force you through the mattress.  You felt the vibrations of his grunts and moans against your neck, and it only served to increase the volume of your own.   

With a frustrated grunt, he pulled away from and out of you, and you whined at the loss of contact.  You were surprised, however, when he flipped you over, gently pressing your chest to the mattress, so your behind was sticking up invitingly in the air. 

You looked back at him with a smirk, “Ohoh, feeling adventurous today are w –” You were cut off, however, by your own scream of pleasure as he entered you in one swift motion.  You two had never done it like this before, and the places he was slamming against were totally unexplored up until now.  He was now deeper in you than he ever had been, all the way to the base, and yet he never slowed his frenzied pounding.

You yelped and moaned into the sheets as he ground into you, your hips bucking up to meet his.  You could feel the crescendo building inside of you again, and as he felt your walls start to tighten, Jean picked up his pace, going faster and harder than he ever had.  You were full on screaming now, your voice starting to crack, and you knew it would be almost nonexistent tomorrow. 

As you started to tip over the edge, his name started to make it in between the pants and moans and yells, growing in volume until he burst inside of you, his hot seed dripping out of you, and shortly after everything unraveled for you as well as you collapsed in a boneless heap on the mattress, legs quivering. 

Jean slid out of you, and you would have whined if you weren’t panting so hard.  You turned over onto your back, and he collapsed on top of you, face pressed into the crook of your neck, arms wrapping around you.  

“You’re heavy,” you groaned, shifting under all of his weight. 

He only grumbled in reply and circled his arms around you tighter.  You felt his erection pressing against your thigh wither and go limp, and you felt a faint spark of disappointment.

“You gonna be okay?” he mumbled into your shoulder, and you understood immediately.

“Yeah, I stopped bleeding around second year of training and haven’t seen a drop since.”

“That can’t be healthy.”

“It’s what happens,” you replied with a shrug, and then there was silence, Jean nuzzling into your shoulder as your eyelids started to flutter.

“Hey, dumbass,” you said sleepily, nudging his shoulder.  “We can’t sleep.  We got shit to do.”

“Screw the fucking chores,” he mumbled, and you could feel his shit-eating grin against your neck.

“Jackass,” you snapped, but you were smiling all the same.  “How about this, we get the fucking chores done, and then I’ll be on top.”

He snapped to attention immediately (in both ways), looking up at you, his eyes sparkling with excitement. 

“Is that a promise?” he asked eagerly.

“Yeah, yeah,” you sighed, rolling your eyes as you reached for your clothes.

~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~

The rest of the gang came back to a hastily cleaned cabin and two very ruffled looking young adults trying to look nonchalant as they read books on the common room couch.

Levi strode in the door, took one look at your hastily braided hair and Jean’s skewed shirt collar, and said irritably, “At _least_ tell me you didn’t fuck in the kitchen.”

Your book hit the floor with a clatter, your face reddening as you whipped around to furiously deny it.  Jean’s voice joined yours, but Levi only rolled his eyes.

“We all know, dumbasses.  You two are almost as obvious as Jaegar and Ackerman.”

Eren, who was just coming inside upon hearing this, tripped over the threshold and landed with a smack on the floor.  Mikasa turned the color of her scarf and promptly proceeded to bury her face in it. 

“Idiots,” Levi snapped as you and Jean scooted as far away from each other as possible, Connie tried to help a blushing Eren from the floor, and Sasha rolled on the ground, clutching her stomach. 

But even so, you did not regret one second of it. 

**Author's Note:**

> idk what to say
> 
> i'm sorry if this sucks i've never even held hands with a male
> 
> perpetuum mobile means something like constant motion if u know what i mean


End file.
